Fiber optic modules can transduce electrical data signals to transmit optical signals serially over optical fibers. Fiber optic modules can transduce optical signals received serially over optical fibers into electrical data signals. The electrical data signals can be coupled into and out of a fiber optic module through a serial data connection or a parallel data connection. A serial data connection can use few serial data input/output pin connections to serially transmit or receive electrical data signals. A parallel data connection uses parallel data input/output pin connections to transmit or receive electrical data signals in parallel. However for the same bit rate over data input/output pin connections, a parallel data connection can transmit data out of or receive data into a fiber optic module at a greater aggregate data rate.
The size or form factor of fiber optic modules is important. The smaller the size or form factor of a fiber optic module, the less space taken on a printed circuit board to which it couples. A smaller size or form factor allows a greater number of fiber optic modules to be coupled onto a printed circuit board to support additional communication channels. It is difficult to provide a parallel data connection for a fiber optic module in a small size form factor.
When a fiber optic module embedded in a system fails it is desirable to replace it, particularly when other communication channels are supported by other operating fiber optic modules. Thus, it is desirable to replace a failed fiber optic module while the system is operational without having to power down the system. It is desirable to plug-in a new fiber optic module while the system is still hot. In a printed circuit board, hot-pluggability is provided on an edge of card by staggering signal traces from the power and ground traces. That is, when a printed circuit board is plugged into a hot system, power and ground are first supplied to the power and ground traces on the printed circuit board before the data signals are applied to signal traces and the circuitry therein. It is easier to provide hot-pluggability for a fiber optic module having a serial data connection because of the few serial data I/O pins. It is more difficult to provide hot-pluggability for a fiber optic module having a parallel data connection because of the higher count of parallel data I/O pins.